Genetics Quiz

review notes, mitosis/meiosis, worksheets

gene

sequence of DNA that codes for a specific protein/trait

allele

version of a gene

genotype

allele combination inherited from the parents

phenotype

physical trait expressed based on the genotype

homozygous

possessing two of the same alleles

homozygous dominant

2 dominant alleles

homozygous recessive

2 recessive alleles

heterozygous

possessing two different alleles

Mendel’s laws

law of segregation, law of independent assortment, law of dominance

law of segregation

during the formation of gametes, the two alleles will segregate, ensuring each gamete carries one allele for each gene

when does law of segregation occur?

anaphase I of meiosis

law of independent assortment

alleles for different genes segregate independently from one another during gamete formation, so the inheritance of one trait does not influence the inheritance of another; only occurs with unlinked genes

when does independent assortment occur?

during metaphase I of meiosis

law of dominance

dominant traits will mask the presence of recessive traits when an individual has a heterozygous genotype

punnett squares

tools used in genetics to predict possible genetic outcomes; helps determine the probability of an offspring inheriting a specific trait

monohybrid

examines one trait

dihybrid

examines the inheritance of two different traits simultaneously

test cross

figures out the unknown genotype (of a trait following simple dominance) of an individual by crossing it with a homozygous recessive individual

how to interpret the results of a test cross

if some of the offspring show the recessive phenotype, the unknown parent is heterozygous; if none of the offspring show the recessive phenotype, the unknown parent is homozygous dominant

multiplication rule

calculates the probability of multiple independent events occurring together/at the same time

addition rule

chance that an event can occur in 2 or more different ways

how to immediately tell if its addition or multiplication?

if its AND, it’s multiplication, and if its OR, it’s addition

incomplete dominance

neither allele is completely dominant over the other, instead, the heterozygous phenotype is a blend

codominance

both alleles are expressed equally in heterozygous phenotypes

multiple alleles

2+ alleles involved in determining phenotype

epistasis

relationship between two different genes; one gene will mask the expression of the other

polygenic inheritance

additive influence of multiple genes on a single trait

sex-linked traits

traits associated with genes found on sex chromosomes

x inactivation

in females, one of the two x chromosomes will become inactivated during embryonic development

non-nuclear DNA

mitochondria and chloroplasts have their own genomes; mom passes them on to her kids

phenotypic plasticity

environmental factors can affect which genes are being expressed, when they are expressed, and how much they are expressed

pedigrees

traces family history for a particular trait

autosomal recessive

requires 2 alleles to appear in phenotype

autosomal dominant

requires 1 allele to appear in phenotype

x-linked recessive

females require 2 alleles, males require 1 allele to appear in phenotype

x-linked dominant

requires at least 1 to appear in phenotype

y-linked (holandric)

only males affected

what does a square represent

males

what does a circle represent

female

what does a shaded in individual mean

that individual expresses the studied trait

what does a half shade mean (will not always be pictured)

carriers

what does a horizontal line connecting 2 individuals represent

marriage

what does a vertical line represent

children

what do the roman numerals represent

generation numbers

what do the numbers under each individual represent

helps identify specific individuals (generation + number)

how are individuals ordered on a pedigree

oldest on the left, youngest on the right

what type of inheritance?

autosomal recessive

what type of inheritance?

autosomal dominant

what type of inheritance?

x-linked recessive

what type of inheritance?

x-linked dominant

what type of inheritance?

y-linked